"And when My servants ask you (O Muhammad concerning Me, then answer them), I am indeed near (to them by My knowledge). I respond to the invocations of the supplicant when he calls on Me (without any mediator or intercessor). So let them obey Me and believe in Me, so that they may be led aright.(2.186)

Imam Ahmad reported that Abu Musa Al-Ash`ari said, “We were in the company of Allah’s Messenger during a battle. Whenever we climbed a high place, went up a hill or went down a valley, we used to say, `Allah is the Most Great,’ raising our voices. The Prophet came by us and said:

(O people! Be merciful to yourselves (i.e., don’t raise your voices), for you are not calling a deaf or an absent one, but One Who is All-Hearer, All-Seer. The One Whom you call is closer to one of you than the neck of his animal. O `Abdullah bin Qais (Abu Musa’s name) should I teach you a statement that is a treasure of Paradise: `La hawla wa la quwwata illa billah (there is no power or strength except from Allah).’)

This Hadith was also recorded in the Two Sahihs, and Abu Dawud, An-Nasa’i, At-Tirmidhi and Ibn Majah recorded similar wordings. Furthermore, Imam Ahmad recorded that Anas said that the Prophet said:

(No Muslim supplicates to Allah with a Du`a that does not involve sin or cutting the relations of the womb, but Allah will grant him one of the three things. He will either hasten the response to his supplication, save it for him until the Hereafter, or would turn an equivalent amount of evil away from him.”) They said, “What if we were to recite more (Du`a).” He said, (There is more with Allah.)

`Abdullah the son of Imam Ahmad recorded `Ubadah bin As-Samit saying that the Prophet said:

(There is no Muslim man on the face of the earth who supplicates to Allah but Allah would either grant it to him, or avert a harm from him of equal proportions, as long as his supplication does not involve sin or cutting the relations of the womb.) At-Tirmidhi recorded this Hadith.